NIHR Signal Ultrasound guided nerve blocks are safe, effective and save time

Published on 7 January 2016

This Cochrane review found that nerve blocks to provide local anaesthesia in the arms or legs of adults before a surgical procedure were safe and effective when guided by ultrasound compared to other guidance techniques. They were successful about nine times out of ten with ultrasound guidance, compared to about eight times out of ten when using other techniques, such as nerve stimulation. Overall, guided blocks were quicker by one minute and caused fewer side effects, such as the accidental puncture of blood vessels. The review did not look at cost-effectiveness, or whether one or another technique was best in a particular block or a particular group of patients. The improved success rates, reduced adverse effect rate and quicker performance time suggest that the use of ultrasound guidance when performing a nerve block for surgery may lead to patient benefits and improved satisfaction. These results support NICE guidance but the costs of ultrasound imaging systems, specialised needles and the training of anaesthetists would also need to be considered in an assessment of affordability and cost-effectiveness of this technique.

Ultrasound guided nerve blocks are safe, effective and save time

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Why was this study needed?

A nerve block is an injection of local anaesthetic to numb the nerves supplying a particular part of the body, such as the arm or leg. It may allow for an operation with the person awake, without the need for a general anaesthetic. Blocks, as an adjunct to a general anaesthetic can improve pain control. It is important to place the injection close to the correct nerve in order to get the maximum benefit and avoid potential complications, such as damaging the nerves or nearby blood vessels.

Various nerve-locating techniques are used. One approach is to use anatomical landmarks, such as bones or arteries. An alternative is electrical nerve stimulation via the injection needle. Muscles supplied by the nerve twitch in time with the pulses of current as the needle nears the nerve. Another approach is to locate the nerve using the images created by ultrasound scan. This is the technology assessed in this review.

What did this study do?

This was a systematic review with meta-analyses of 32 randomised controlled trials that compared ultrasound-guided arm or leg nerve blocks in adults with at least one other method of nerve location. It was an update of a previous 2009 review to include new trials. Twenty-six trials looked at nerve blocks in the arm or hand, and six in the leg or foot. Trials were excluded if they looked at postoperative pain relief only, or were for the treatment of chronic pain.

Seventeen trials compared ultrasound with nerve stimulation while nine compared ultrasound in combination with nerve stimulation versus nerve stimulation alone. The remaining six studies looked at a variety of other techniques.

The review used reliable Cochrane systematic review methods. However, there was a high risk of bias across all included studies caused by, for example, a lack of blinding and missing information on how the procedure was performed. Therefore, the findings need to be treated with caution.

What did it find?

  • Ultrasound guided nerve blocks were successful, i.e. giving sufficient anaesthesia for surgery, about 90% of the time, compared to a success rate of about 80% when using other techniques (odds ratio [OR] 2.94, 95% confidence interval [CI] 2.14 to 4.04). They were also less likely to need supplementary nerve blocks or general anaesthetic (OR 0.28, 95%CI 0.20 to 0.39).
  • Accidental puncture of blood vessels was a complication in about two in 100 ultrasound-guided nerve blocks compared to nearly ten in 100 procedures using other techniques (OR 0.19, 95% CI 0.07 to 0.57). Ultrasound also led to fewer nerve-related complications such as ‘pins and needles’ - about eight per 100 compared with 17 per 100 with other techniques (OR 0.42, 95% CI 0.23 to 0.76). However, the quality of this evidence was low, with wide variation in results between trials.
  • Ultrasound-guided nerve blocks were performed about one minute faster than when using other guidance techniques (nerve blocks typically take about five to ten minutes to do). Again, the reliability of this evidence was assessed as very low.

What does current guidance say on this issue?

NICE 2009 guidance supports the use of ultrasound-guided regional nerve blocks. It recommends that clinicians wishing to perform the procedure should be experienced in the administration of regional nerve blocks and trained in ultrasound guidance techniques.

What are the implications?

The evidence in this review confirms and supports NICE guidance that ultrasound may be useful to guide nerve block in adults requiring local anaesthesia in the arms or legs. The review did not assess cost-effectiveness. However, as ultrasound guidance is more effective and takes less time to perform than other regional techniques, its increased use may result in some cost savings. Balancing the effectiveness, safety, cost and training requirements for undertaking procedures by regional anaesthesia compared to general anaesthesia is an important consideration not addressed by this review. Given the overall high costs associated with surgery under general anaesthesia and the possible changes to treatment pathways that result from increased use of nerve blocks, further real world data on activity and cost would help commissioning decisions in this area.

It should be noted that these results are only applicable to nerve blocks of the upper and lower limbs in adults for operative pain relief. Further systematic reviews would be required to assess whether these findings are consistent with other nerve blocks. Neither did the included studies consistently describe who performed the nerve block. Therefore it is not possible to say whether the success of ultrasound-guided nerve block is influenced by experience or the level of technical expertise.

Regional anaesthesia has become more commonly used in the UK in the last decade and there are implications for the training of anaesthetists and surgical/anaesthetic pathways from any further increases in use of ultrasound guidance.

Citation

Lewis SR, Price A, Walker KJ, et al. Ultrasound guidance for upper and lower limb blocks. Cochrane Database Syst Rev. 2015;9:CD006459.

Bibliography

NHS Chocies. Local anaesthesia. London: NHS Choices; 2015.

NHS Chocies. Ultrasound scan. London: NHS Choices; 2015.

NICE. Ultrasound-guided regional nerve block. IPG285. London: National Institute for Health and Care Excellence; 2009.

Marhofer P, Harrop-Griffiths W, Kettner SC, et al. Fifteen years of ultrasound guidance in regional anaesthesia: Part 1. Br J Anaesth. 2010;104(5):538-546.

Why was this study needed?

A nerve block is an injection of local anaesthetic to numb the nerves supplying a particular part of the body, such as the arm or leg. It may allow for an operation with the person awake, without the need for a general anaesthetic. Blocks, as an adjunct to a general anaesthetic can improve pain control. It is important to place the injection close to the correct nerve in order to get the maximum benefit and avoid potential complications, such as damaging the nerves or nearby blood vessels.

Various nerve-locating techniques are used. One approach is to use anatomical landmarks, such as bones or arteries. An alternative is electrical nerve stimulation via the injection needle. Muscles supplied by the nerve twitch in time with the pulses of current as the needle nears the nerve. Another approach is to locate the nerve using the images created by ultrasound scan. This is the technology assessed in this review.

What did this study do?

This was a systematic review with meta-analyses of 32 randomised controlled trials that compared ultrasound-guided arm or leg nerve blocks in adults with at least one other method of nerve location. It was an update of a previous 2009 review to include new trials. Twenty-six trials looked at nerve blocks in the arm or hand, and six in the leg or foot. Trials were excluded if they looked at postoperative pain relief only, or were for the treatment of chronic pain.

Seventeen trials compared ultrasound with nerve stimulation while nine compared ultrasound in combination with nerve stimulation versus nerve stimulation alone. The remaining six studies looked at a variety of other techniques.

The review used reliable Cochrane systematic review methods. However, there was a high risk of bias across all included studies caused by, for example, a lack of blinding and missing information on how the procedure was performed. Therefore, the findings need to be treated with caution.

What did it find?

  • Ultrasound guided nerve blocks were successful, i.e. giving sufficient anaesthesia for surgery, about 90% of the time, compared to a success rate of about 80% when using other techniques (odds ratio [OR] 2.94, 95% confidence interval [CI] 2.14 to 4.04). They were also less likely to need supplementary nerve blocks or general anaesthetic (OR 0.28, 95%CI 0.20 to 0.39).
  • Accidental puncture of blood vessels was a complication in about two in 100 ultrasound-guided nerve blocks compared to nearly ten in 100 procedures using other techniques (OR 0.19, 95% CI 0.07 to 0.57). Ultrasound also led to fewer nerve-related complications such as ‘pins and needles’ - about eight per 100 compared with 17 per 100 with other techniques (OR 0.42, 95% CI 0.23 to 0.76). However, the quality of this evidence was low, with wide variation in results between trials.
  • Ultrasound-guided nerve blocks were performed about one minute faster than when using other guidance techniques (nerve blocks typically take about five to ten minutes to do). Again, the reliability of this evidence was assessed as very low.

What does current guidance say on this issue?

NICE 2009 guidance supports the use of ultrasound-guided regional nerve blocks. It recommends that clinicians wishing to perform the procedure should be experienced in the administration of regional nerve blocks and trained in ultrasound guidance techniques.

What are the implications?

The evidence in this review confirms and supports NICE guidance that ultrasound may be useful to guide nerve block in adults requiring local anaesthesia in the arms or legs. The review did not assess cost-effectiveness. However, as ultrasound guidance is more effective and takes less time to perform than other regional techniques, its increased use may result in some cost savings. Balancing the effectiveness, safety, cost and training requirements for undertaking procedures by regional anaesthesia compared to general anaesthesia is an important consideration not addressed by this review. Given the overall high costs associated with surgery under general anaesthesia and the possible changes to treatment pathways that result from increased use of nerve blocks, further real world data on activity and cost would help commissioning decisions in this area.

It should be noted that these results are only applicable to nerve blocks of the upper and lower limbs in adults for operative pain relief. Further systematic reviews would be required to assess whether these findings are consistent with other nerve blocks. Neither did the included studies consistently describe who performed the nerve block. Therefore it is not possible to say whether the success of ultrasound-guided nerve block is influenced by experience or the level of technical expertise.

Regional anaesthesia has become more commonly used in the UK in the last decade and there are implications for the training of anaesthetists and surgical/anaesthetic pathways from any further increases in use of ultrasound guidance.

Citation

Lewis SR, Price A, Walker KJ, et al. Ultrasound guidance for upper and lower limb blocks. Cochrane Database Syst Rev. 2015;9:CD006459.

Bibliography

NHS Chocies. Local anaesthesia. London: NHS Choices; 2015.

NHS Chocies. Ultrasound scan. London: NHS Choices; 2015.

NICE. Ultrasound-guided regional nerve block. IPG285. London: National Institute for Health and Care Excellence; 2009.

Marhofer P, Harrop-Griffiths W, Kettner SC, et al. Fifteen years of ultrasound guidance in regional anaesthesia: Part 1. Br J Anaesth. 2010;104(5):538-546.

Ultrasound guidance for upper and lower limb blocks

Published on 12 September 2015

Lewis, S. R.,Price, A.,Walker, K. J.,McGrattan, K.,Smith, A. F.

Cochrane Database Syst Rev Volume 9 , 2015

BACKGROUND: Peripheral nerve blocks can be performed using ultrasound guidance. It is not yet clear whether this method of nerve location has benefits over other existing methods. This review was originally published in 2009 and was updated in 2014. OBJECTIVES: The objective of this review was to assess whether the use of ultrasound to guide peripheral nerve blockade has any advantages over other methods of peripheral nerve location. Specifically, we have asked whether the use of ultrasound guidance:1. improves success rates and effectiveness of regional anaesthetic blocks, by increasing the number of blocks that are assessed as adequate2. reduces the complications, such as cardiorespiratory arrest, pneumothorax or vascular puncture, associated with the performance of regional anaesthetic blocks SEARCH METHODS: In the 2014 update we searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2014, Issue 8); MEDLINE (July 2008 to August 2014); EMBASE (July 2008 to August 2014); ISI Web of Science (2008 to April 2013); CINAHL (July 2014); and LILACS (July 2008 to August 2014). We completed forward and backward citation and clinical trials register searches.The original search was to July 2008. We reran the search in May 2015. We have added 11 potential new studies of interest to the list of 'Studies awaiting classification' and will incorporate them into the formal review findings during future review updates. SELECTION CRITERIA: We included randomized controlled trials (RCTs) comparing ultrasound-guided peripheral nerve block of the upper and lower limbs, alone or combined, with at least one other method of nerve location. In the 2014 update, we excluded studies that had given general anaesthetic, spinal, epidural or other nerve blocks to all participants, as well as those measuring the minimum effective dose of anaesthetic drug. This resulted in the exclusion of five studies from the original review. DATA COLLECTION AND ANALYSIS: Two authors independently assessed trial quality and extracted data. We used standard Cochrane methodological procedures, including an assessment of risk of bias and degree of practitioner experience for all studies. MAIN RESULTS: We included 32 RCTs with 2844 adult participants. Twenty-six assessed upper-limb and six assessed lower-limb blocks. Seventeen compared ultrasound with peripheral nerve stimulation (PNS), and nine compared ultrasound combined with nerve stimulation (US + NS) against PNS alone. Two studies compared ultrasound with anatomical landmark technique, one with a transarterial approach, and three were three-arm designs that included US, US + PNS and PNS.There were variations in the quality of evidence, with a lack of detail in many of the studies to judge whether randomization, allocation concealment and blinding of outcome assessors was sufficient. It was not possible to blind practitioners and there was therefore a high risk of performance bias across all studies, leading us to downgrade the evidence for study limitations using GRADE. There was insufficient detail on the experience and expertise of practitioners and whether experience was equivalent between intervention and control.We performed meta-analysis for our main outcomes. We found that ultrasound guidance produces superior peripheral nerve block success rates, with more blocks being assessed as sufficient for surgery following sensory or motor testing (Mantel-Haenszel (M-H) odds ratio (OR), fixed-effect 2.94 (95% confidence interval (CI) 2.14 to 4.04); 1346 participants), and fewer blocks requiring supplementation or conversion to general anaesthetic (M-H OR, fixed-effect 0.28 (95% CI 0.20 to 0.39); 1807 participants) compared with the use of PNS, anatomical landmark techniques or a transarterial approach. We were not concerned by risks of indirectness, imprecision or inconsistency for these outcomes and used GRADE to assess these outcomes as being of moderate quality. Results were similarly advantageous for studies comparing US + PNS with NS alone for the above outcomes (M-H OR, fixed-effect 3.33 (95% CI 2.13 to 5.20); 719 participants, and M-H OR, fixed-effect 0.34 (95% CI 0.21 to 0.56); 712 participants respectively). There were lower incidences of paraesthesia in both the ultrasound comparison groups (M-H OR, fixed-effect 0.42 (95% CI 0.23 to 0.76); 471 participants, and M-H OR, fixed-effect 0.97 (95% CI 0.30 to 3.12); 178 participants respectively) and lower incidences of vascular puncture in both groups (M-H OR, fixed-effect 0.19 (95% CI 0.07 to 0.57); 387 participants, and M-H OR, fixed-effect 0.22 (95% CI 0.05 to 0.90); 143 participants). There were fewer studies for these outcomes and we therefore downgraded both for imprecision and paraesthesia for potential publication bias. This gave an overall GRADE assessment of very low and low for these two outcomes respectively. Our analysis showed that it took less time to perform nerve blocks in the ultrasound group (mean difference (MD), IV, fixed-effect -1.06 (95% CI -1.41 to -0.72); 690 participants) but more time to perform the block when ultrasound was combined with a PNS technique (MD, IV, fixed-effect 0.76 (95% CI 0.55 to 0.98); 587 participants). With high levels of unexplained statistical heterogeneity, we graded this outcome as very low quality. We did not combine data for other outcomes as study results had been reported using differing scales or with a combination of mean and median data, but our interpretation of individual study data favoured ultrasound for a reduction in other minor complications and reduction in onset time of block and number of attempts to perform block. AUTHORS' CONCLUSIONS: There is evidence that peripheral nerve blocks performed by ultrasound guidance alone, or in combination with PNS, are superior in terms of improved sensory and motor block, reduced need for supplementation and fewer minor complications reported. Using ultrasound alone shortens performance time when compared with nerve stimulation, but when used in combination with PNS it increases performance time.We were unable to determine whether these findings reflect the use of ultrasound in experienced hands and it was beyond the scope of this review to consider the learning curve associated with peripheral nerve blocks by ultrasound technique compared with other methods.

Ultrasound scans use high-frequency sound waves that are reflected by different structures within the body, such as nerves, blood vessels and muscles, and are captured by the equipment and turned into an image which is displayed on a monitor. This can be used to guide the needle during the procedure to deliver the local anaesthetic close to the intended nerve and to avoid unintentional damage to nearby structures.

Expert commentary

This review supports the routine use of ultrasound guided nerve block techniques. Its use provides advantages in all aspects of regional anaesthesia practise, including quality of block and performance time. We need to establish ultrasound guided techniques as the new standard of practice for the UK that may have retraining implications. In many studies the expertise of the clinicians was unknown, but my personal opinion is that the use of ultrasound offers advantages irrespective of clinician experience. Ultrasound is a 2-D image of 3-D anatomy and therefore complications may still occur. Adding a nerve stimulator to an ultrasound technique (dual guidance) and an injection pressure monitor (triple guidance) may reduce the rate of complications and side effects, but this has been demonstrated to increase block performance time. Regional anaesthesia complications are so rare that a national block registry or national database may be the only way to establish incidence.

Dr Morné Wolmarans, RA-UK President and Consultant Anaesthetist, Norfolk & Norwich University Hospital